/Engine/Source/Runtime/RenderCore/Public/RenderGraphBuilder.h
Register an external texture with a custom name. The name is only used if the texture has not already been registered.
FRDGTextureRef RegisterExternalTexture ( const [TRefCountPtr](API\Runtime\Core\Templates\TRefCountPtr)< [IPooledRenderTarget](API\Runtime\RenderCore\IPooledRenderTarget) > & ExternalPooledTexture, const TCHAR * NameIfNotRegistered, ERDGTextureFlags Flags )